I got my A2 about 6 weeks ago and use it primarily while walking on the treadmill. I didn't notice until quite recently that even with headphones plugged in, the audio is still completely audible through the external speakers. Has anyone else experienced this or know how to turn it off? I've tried several sets of headphones and it's the same with each set. I'd like to take the A2 on a trip soon and I don't think the rest of the airplane will be interested in listening to Harry Potter...